The invention relates to digital data processing and, more particularly, to image compression and decompression. It has application, by way of non-limiting example, in the compression of two- and three-dimensional images for storage and/or remote visualization.
Digital data processors are increasingly used for the acquisition, transfer, storage, analysis and display of images. In many industries, their use is the norm, having long ago supplanted competing technologies, such as photochemical media (e.g., recording films) for storage and telefax machines for transmission. This is the natural outgrowth of increases in storage capacity and processing power of today's digital data processors, as well as of ubiquitous high-speed digital networks supporting communications among those devices.
Notwithstanding these advances, storage and transmission of digital images remain the bane of image processing system designers and users alike. Whereas faster backplanes and increased use of image co-processors (such as graphics processing units, or “GPUs”) have brought image processing and display speeds to acceptable levels—even on desktop and laptop computers—image data is often too large for storage, in quantity, on typical disk drives (or other storage devices) or for rapid transmission over local area networks, wide area networks, and “internets,” by way of example.
As a consequence, image compression—i.e., the systematic reduction of the number of “bits” (or other information-bearing units) representing an image—is typically used to reduce image sizes for both storage and transmission. The converse, image decompression, is used to reconstitute an image for processing or display. Common compression techniques exploit bit patterns within the original image (such as in run-length encoding) and/or mathematical transformations of image regions (such as in JPEG encoding).
Regardless of the technique used, image compression and decompression are computationally intensive. In most digital data processor implementations, these tasks are handled on the central processing unit, or “CPU.” While this affords the flexibility that is often demanded by compression algorithms, it can have the effect of bringing down overall digital data processor performance.
Accordingly, an object of this invention is to provide improved methods and apparatus for digital data processing. A more particular object is to provide such methods and apparatus for image compression and/or decompression.
Related objects of the invention are to provide such methods and apparatus as facilitate data storage and/or transmission. Still further related objects are to provide such methods and apparatus as facilitate remote image viewing.
Further objects of the invention are to provide such methods and apparatus as more fully utilize the processing resources found in typical digital data processors.
Still further objects of the invention are to provide such methods and apparatus as can be implemented at reasonable cost on legacy, current, and future digital data processing systems.